Control mechanism



March 29, 1938. H. J. MASTENBROOK CONTROL MECHANISM Filed April 6, 1957 INVENTOR.

K s 0 m B 7 O N n mfw M 1r M Patented Mar. 29, 1938 UNITED STATES CONTROL Henry J. Mastenbrcok,

to lhe Swartwout Company, Clev corporation of Ohio Application April 6,

Claims.

This invention relates to a method and means for afiecting a control responsive to the flow of steam, and is particularly adapted, though not necessarily limited in its application, to the regu- 5 lation of flow of feed water where it is desired to influence the same with respect to changes in boiler load. In using the word steam I also have in mind steam from fluids other than water. In its broader aspects my invention provides a controllable liquid or water column in a fluid circuit with steam or other fluid in which the range of the rise and fall of the liquid column may, by virtue of the difference in heat content, temperature, density or mass, as compared with the adjacent steam or other fluid, be used to create or modify force or motion available for the control which may be desired to be affected.

For the sake of illustrating the utility of and advantages of my invention, the following de" scription will deal largely with its application to the control of feed water in response to steam flow from a boiler. In this connection I have particularly disclosed a thermo-responsive mechanism within which the variations in water level adjacent a steam column create available force and motion by virtue of the difference in the temperature or heat content between the steam and water. Of the various instrumentalities responsive in this manner, I have chosen to illustrate my invention with a thermo-responsive device of the pressure generator type following generally the teaching of the Copley Patent 1,193,125, the functions of which, so far as they enter into the practice of my invention, are now well known in the art and are commonly carried out in a wide variety of equivalent instrumentalities.

The desirability of supplying feed water to a boiler more or less in accordance with the boiler load has long been recognized. Numerous arrangements have been proposed whereby the feed water supply is controlled by a valve which is opened and closed by a combination of instrumentalities which reflect variations in both boiler water level and load. Among the patents relating to such arrangements may be noted the Barrett Patent No. 1,820,423 which discloses a fluid pressure operated feed water valve connected to separate pressure generators, one of which is responsive to variations in boiler water level and the other to variations in the boiler load. In the Barrett arrangement the water level pressure generator or other thermo-responsive device is disposed substantially at the normal boiler water level and the generators which are responsive to boiler load are disposed on an elongated MECHANISM Cleveland, Ohio, assignor eland, Ohio, a

1937, Serial No. 135,297

manometer tube, one end of which is connected to the boiler drum just above the water level and the other end beyond the boiler nozzle. This tube is necessarily of such length as to carry a water column having a hydrostatic head equal to the maximum difference in pressures which may exist between the boiler drum and the boiler nozzle under any load on the boiler. One leg of the manometer tube is provided with a plurality of pressure generators connected in series and variations in the water level in the manometer tube, due to variations in boiler load, are reflected in the pressure output of the series connected generators. This pressure output was applied, with the pressure of the boiler water level generator, to the feed water valve.

Excellent feed water regulation has been obtained by arrangements of the type noted above. However, the length of the manometer tube, which is necessary in most instances to provide the hydrostatic head required to balance the pressure drop, is a serious obstacle to the installation and flexibility of operation and use of this system and may make impracticable its use with already installed boilers. Other types of boiler load controlled feed water regulators have also been pro posed but these also, for various reasons, have serious inherent defects and limitations greatly restricting their function and range of operations and results.

It is among the broader objects of my invention to provide a means which is readily adaptable for attachment to or association with a steam pipe, for example, and which is susceptible of compensating for the wide range of pressure differentials between points to which attachment can readily be made, and which in turn can be adjusted to reflect by either force or motion an indication of the rate of flow from which other mechanism sought to be controlled with respect to the rate of steam flow may be governed,

It is another object of my invention to provide means by which a relatively great pressure differential arising from the rate of flow of steam through a conduit may, by simple means, be translated into a small but substantially proportioned rise and fall of a water column or a steam and water column, whereby either the thermal effect or otherwise from the varying height of the water column may be used to effect the control of devices sought to be controlled with respect to the rate of flow of steam.

It is also among the objects of the present invention to provide an arrangement in which a fluid pressure controlled feed water valve is responsive to a generated pressure which varies in accordance with variations in boiler load and means for generating such pressure which occupy a minimum space and do not possess the disadvantages of previously proposed load responsive devices. Other objects of my invention are: the provision of boiler load responsive means for actuating a feed water valve which may be readily adjusted and regulated to cover the particular operating conditions encountered in any given installation; the provision of a combined water level and load control for a boiler feed water valve in which the proportionate influence of the load responsive means upon the feed water valve may be readily adjusted to secure the desired operation of the system; the provision of a flexible, boiler load responsive, fluid pressure generator hook-up in which any desired percentage of the pressure drop between any two points in the steam system may be utilized and applied to a pressure generator or other thermoresponsive device; and the provision of load responsive thermo-responsive means of the type described which can be installed without the necessity of a special orifice or other means for creating a pressure drop.

The above and other objects of my invention will appear from a description of one illustrative embodiment thereof, reference being had to the accompanying drawing which illustrates, in a diagrammatic manner, an application of my invention to a load controlled feed water regulating system, and in which:

Figure 1 shows the general arrangement of the apparatus, and

Figure 2 is a view taken on line 22 of Figure l and showing the generator and gauge glass assembly.

The boiler I may be of the water tube type as illustrated and a desirable normal water level therein has been indicated at W. A feed water regulator, preferably of the thermo-responsive type such as a pressure generator 2, is disposed across the water level W at one end of the boiler I. The generator 2 is connected to the boiler through a suitably valved connection 3, above the water level, and a similarly valved connection 4 below the water level W. The generator itself, as illustrated, is of well known type, preferably as disclosed in the prior Copley Patent No. 1,193,125 or in my prior Patent No. 1,923,320, and consists essentially of a pipe 5 extending through a closed tubular shell 6. Cooling fins "I may be secured to the shell I3 and a tube 8 extends from the closed chamber formed between the outside of the pipe 5 and the inside of the shell 6. The pipe 5 is connected across the boiler water level and variations in the water level will cause corresponding variations of the liquid level in the pipe 5. Thus, a greater or lesser amount of this pipe will be exposed to steam and a suitable fluid in the chamber between the shell 6 and pipe 5 will be heated to a degree or extent which varies with fluctuations in the boiler water level. This fluid medium will expand or contract or will volatilize and generate a pressure which reflects the water level W and this pressure may be applied through the tube 8 to the diaphragm chamber 9 of the feed water valve I which is disposed in the feed water line II. The valve IIJ may be of any suitable type which is so arranged that when the pressure exerted on the diaphragm through the pipe 8 increases, due to falling of the water level W, the valve II] will open proportionately to the pressure generated and permit more water to enter the boiler through the pipe II.

The boiler load responsive portion of this feed Water regulating apparatus, illustrates the essential characteristics of my invention and comprises preferably a pressure generator I2 which may be similar in all respects to the generator 5. Such a generator may also follow the teaching of my prior patent both as to its function and adjustable mounting, and for the purpose of this application may be considered as illustrative of any thermo-responsive device which reacts to variations in the height of the steam and water column to which it is responsive. A liquid level responsive device, suitably connected to affect the feed water valve in response to changes in the height of a water column, would also be practicable in carrying out the broad aspects of my invention. This generator I2 is adjustably mounted, preferably as disclosed in my prior Patent No. 1,923,320, and connected by suitable pipes across any portion of the steam system where a pressure drop occurs which varies with boiler load, which drop is at least sufficient to operate the generator I2 as by changing the water level throughout the effective vertical height thereof, whereby variations in load will cause corresponding changes in the pressure generated. In the illustrated installation the generator I2 is connected across a non-return valve, indicated at I3, or other handy obstruction or orifice in the steam line I4. Those skilled in the art will appreciate that suitable connections on the principle of a Pitot tube may also be used where a restriction in the pipe is not as conveniently available. When the connection is made across the non-return valve, a check valve is preferably interposed as at I3 to maintain the original function of the non-return valve I3. That is, when my installation is made across a non-return valve I prefer that there be no possibility of unwanted return of fluid into the boiler through the connections incident to the installation of a device following my invention. Moreover, I appreciate that without a check valve in my connections, a back flow of steam into the boiler under emergency or other open the feed valve at an undesired or undesirable time.

The pipe I5, containing the check valve I3 and the hand valve I'I, leads from the steam main I4 on the upstream side of the non-return valve I3 to a T I. Preferably from the side of the T I5, that is out of the direct line of flow therethrough, is taken off the upper generator conduit lead I6 of preferably reduced size and containing suitable swivelled joints as shown in my said prior patent and a hand valve I6. The lower generator conduit I9, suitably jointed as in my prior patent, leads through a handy valve and a condensate cooling reservoir 22 to the T 23. A generator blow down, alve I9 is preferably provided as shown. The connection between the reservoir 22 and the T 23 is also preferably on the side of the T whereby the direct flow from the pipe I5 is through the T I5, shunt pipe 25 (preferably larger in diameter than pipe I5), hand valve 26, T 23 and pipe 24 through hand valve 2I back to the steam main I4 on the downstream side of the valve I3.

The reservoir 22 is positioned to maintain a condensate level W W below which all or part of the generator I2 may be adjustably disposed. Assuming the pressure chamber of the generator conditions might heat up the generator I2 and tend to 12 to be, when cool, substantially full of liquid, then to chill the whole generator, it is necessary to have a head of condensate available sufficient to displace substantially all steam in the inner generator conduit.

To give a wider range of adjustability and to increase the facility with which a desired minimum pressure differential between the Ts l5 and 23 may be obtained, I prefer in an illustrative instance that the pipe 15 to the T l5 be one inch pipe; that the shunt pipe 25 be an inch and a quarter pipe; that the piping within the generator system, that is, from the T l5 to the T 23, be of smaller diameter than either of the above pipes, such, for example, as half inch pipe; and that the pipe 24 from the T 23 back to the steam main be one inch pipe, so that when desired a very small minimum differential, i. e., that incident to the drop-through the pipe 25 of the larger diameter, will be available. By throttling the valve 26, this differential can, of course, be increased up to about the full differential across a non-return valve l3 in the steam main.

A tube 21, from the pressure chamber of the generator I2, is connected to the tube 8 so that the combined pressures of the generators 5 and I2'will be effective upon the diaphragm 9 of the feed water valve I0. As described above, when the boiler is in operation, variations in the boiler water level W will be reflected by corresponding changes in the pressure supplied from the generator 2 to the feed Water valve ID through the pipe or tube 8. Variations in the boiler load, which will cause variations in the rate of steam flow through the pipe M, will be reflected by variations in the pressure generated by the generator I2 and applied to the feed water valve through the pipe or tube 21. The combined action of these two pressure generators may be so proportioned and regulated that feed water is supplied to the boiler in the most effective manner regardless of extreme variations in load, and the control may be adjusted so that variations in load may have more or less effect on the feed water regulation.

For purposes of explanation, it may be assumed that the normal pressure drop across the non-return valve 13 at the condition of maximum boiler load is four pounds per square inch. With the apparatus of the Barrett Patent No. 1,820,423 it would be necessary to supply a manometer tube and generator having a water column high enough to support the maximum pres sure differential, in this case about nine feet of water. This requisite would, in many cases, necessitate a tube and generator or other thermoresponsive means of such length as to prevent practical installation. In the present system the pressure drop which is effective upon the water level in the inner conduit of the generator i2 may be reduced to substantially any small desired value by means of the by-pass or shunt pipe connection 25 and the valves controlling the flow therethrough. For example, pinching down the valve I"!- while opening wide the valve 26 will reduce the pressure drop between the Ts l5 and 23 substantially to zero even when the drop across the valve I3 is great. Conversely when the valve i1 is wide open and the valve 26 substantially shut, the drop between the Ts I5 and 23 will tend to equal that across the valve 13. Thus the whole range of differential pressures between the Ts l5 and 23 may be selected and reduced to a few or any desired number of inches of water varying within such range in substantial proportion tothe drop across the valve 13 and the steam flow. The level of the water in the inner tube of generator l2 at maximum load may be adjusted by these valves, and the total variation inthis water level from no load to full load may also be selectively established so that with the adjustment of the position of the generator i2, any desired amount or character of load control may be imposed upon the feed water valve. The load variations may be made to be the major influence in the feed Water control or the load influence may be reduced to zero if a pure water level control is desired.

In the operation above described the excess of. pressure in the pipe It over the pressure in the reservoir 22, lowers the condensate level in the inner pipe of the generator 52, thereby bringing steam down in the said inner pipe and heating the contents of the generator. At the water level in the inner pipe of the generator there is a continual accumulation of condensate causing a flow of condensate into the reservoir 22 with a resultant overflow into the pipe 25. The overflow is small enough to be easily picked up in the steam main M without substantial impairment of the quality of the steam therein. This continual condensation brings about a corresponding flow of steam through the pipe l6 into the inner tube of the generator, in view of which a further refinement in the response of the gen erator to the steam flow in the main l4 may be had through adjustment of the valve IS.

The reservoir 22 is preferably provided with cooling fins and the radiation therefrom and from the conduit l9 and the body of the generator l2 insures an adequate supply of cool' condensate to chill the generator quickly when the boiler load drops off.

The generator l2 may be advantageously supplied with a gauge glass l 2 which extends alongside of the generator and gives a visual indication of the water level in the inner pipe of the generator. When placing the apparatus into operation the valves I1, 26 and I6 will be adjusted until the fluctuations in the gauge glass i2, and consequently in the inner pipe of the generator 12, will lie within the desired limits relative to the vertical position of the generator even during maximum fluctuation in the boiler load, it being understood that the valves 20 and 21, though being susceptible of use in lieu of the valves l6 and ii respectively may be left wide open in normal operation. Further, the valves l! and 26 may be so set, and the vertical position of the generator 42 and its angle of inclination may be so varied through the flexible hook-up provided by the pipes 16 and 19 that substantially any desired amount or character of response may be obtained from the generator in response to a change in boiler load. Thus, as noted above, the feed water control may be made largely responsive to boiler load or largely responsive to water level by the ready adjustment provided without shutting down the boiler or interrupting its operation.

As the boiler load increases the pressuredrop across the valve 13 will increase and this variation, proportionately reduced as desired, will cause the water in the inner pipe of the generator 12 to be forced down thus permitting'a greater heating of the fluid in the outer generator chamber causing an increase in the pressure supplied to the feed water valve it! through the pipe 21, and the valve it! will be urged toward open position, permitting water to be fed to the boiler, or increasing the flow thereto.

It has been demonstrated above that the adjustment, particularly on the valves of I! and 26, will determine the upper and lower limits of the movement of the water .column within the inner generator tube from zero to maximum flow through the steam main. Assuming, for example, that the efiective length of the generator is six inches, that is, its length is such that when in a vertical position the generated pressure changes from its minimum to a maximum as the Water level within its inner tube rises or falls through six inches of height, then it will be seen that when the generator is positioned vertically within the exact limits of a. six inch rise and fall of the water column, the generator pressure will change from its minimum to its maximum substantially in proportion to the rate of flow of steam from zero to maximum flow. It should also be understood that if then the generator were bodily lowered three inches no change in generator pressure would be expected until the rate of steam flow had caused the water level to drop about three inches, i. e., to get down to the lowered position of the generator. In this manner the steam flow effect could be held at zero until a rate had been found when it was desired to cut in the steam flow effect. Carrying on the same example, for illustration, the generator might be inclined with respect to the vertical, and disposed in whole or in part within the range of fluctuation in the water level, so that its whole generated pressure from minimum to maximum could be brought about within any fractional part of the vertical change in the water level. In any position of the generator the whole range ofchange of water level can, of course, be altered by adjustment of the valves I1 and 26, for example, and thus a great range of kinds and characters of control, measured in terms of generated pressure as against the rate of flow of steam, can be readily obtainable.

Although I have illustrated and described my invention as applied to a simple Water tube type boiler provided with a single feed water supply, it will be understood that if desired a plurality of generators l2 may be connected in parallel and the pressure outputs of these generators used to control or operate a plurality of feed water valves or other instrumentalities. The flow generator l2 may operate a feed valve without interconnection to a water level responsive regulator when simple load control is wanted on such a valve. It will also be understood that, if desired, an orifice plate may be inserted in the steam line to provide a pressure drop which varies with variations in boiler load. Further, if not convenient or desirable to install such an orifice, any portion of the system where a suiflcient pressure drop occurs may be utilized and by regulating my by-pass connection a suitable relatively small pressure differential may be applied to the pressure generator so that it will be responsive to the complete range of boiler load variations. I have found in practice that a pressure drop equal to four inches of water is suflicient and satisfactory for proper operation of my generator and I have been able to reduce the pressure drop from approximately four pounds to four inches of water with a minimum of piping and in a very small space by the use of my improved hook-up.

Although I have illustrated and described an embodiment of my invention as applied to controlling a feed water valve, it will be understood that its utility and range of use is by no means limited to that specific use, since any manner of instrumentalities sought to be made responsive to the rate of fluid flow may be advantageously controlled within the precepts of my invention.

In this specification and the accompanying drawing one embodiment of my invention has been illustrated and described. It will appear to those skilled in the art, however, that variations and modifications may be made in the specific arrangement herein disclosed without departing from the spirit of my invention. I do not therefore wish to be limited to the specific form illustrated but claim as my invention all embodiments coming within the scope of the appended claims.

I claim:

1. In a boiler feed water system, a thermoresponsive device connected across parts of the steam system between which a pressure differential exists, which pressure difierential varies with changes in boiler load, a feed water valve, means connecting said feed water valve to said thermo-responsive device and a by-pass conduit around said thermo-responsive device.

2. In a boiler feed water system, a thermoresponsive device connected across parts of the steam system between which a pressure difierential exists, which pressure differential varies with changes in boiler load, a feed water valve, means connecting said feed water valve to said thermo-responsive device, a by-pass conduit around said thermo-responsive device and means for regulating the flow of steam through said by-pass conduit.

3. In a boiler control apparatus, thermoresponsive means having a liquid level adapted to vary with variations in boiler load, said means being connected across a portion of the steam system of the boiler in which a pressure drop exists during normal operation of the boiler, and an adjustable by-pass connection around said thermo-responsive device whereby pressure effective to vary the liquid level of the thermoresponsive device may be controlled.

4. In a boiler feed water system, a feed water valve, load responsive means for controlling the operation of said feed water valve, said load responsive means including a conduit connected across a portion of the boiler steam system in which a pressure drop exists during normal boiler operation, means for maintaining in said conduit a fluid level which varies with variations in boiler load, means responsive to said fluid level variations for actuating said feed water valve and a b y-pass connection around said conduit in which said fluid level is maintained.

5. In a boiler feed water system, a feed water valve, load responsive means for controlling the operation of said feed water valve, said load responsive means including a conduit connected across a portion of the boiler steam system in which a pressure drop exists during normal boiler operation, means for maintaining in said conduit a fluid level which varies with variations in boiler load, means responsive to said fluid level variations for actuating said feed water valve, a by-pass connection around said conduit in which said fluid level is maintained, and means for adjusting said by-pass connection to vary the pressure efiective upon said fluid level in said conduit.

6. In combination, means through which steam may flow against a substantial resistance, fluid conducting means connected to said first named means at spaced points in a' manner whereby steam tends to flow therethrough substantially in proportion to the flow through said first named means, a by-pass and valve means in said fluid conducting means whereby the fluid pressure drop across said by-pass may be selectively adjusted in amounts less than that existing across said resistance to reflect the rate of flow of steam, a condensate column in said conducting means in parallel with said by-pass, and means responsive to the height of said condensate column exerting measurable forces substantially proportionate to the rate of flow of steam in said first named means.

'7. The combination of claim 6 in which the by-pass possesses a lesser resistance to flow than the balance of said fluid conducting means, and means in said by-pass for adjustably increasing the resistance to the flow of fluidtherethrough.

8. In combination, a steam system embracing points between which a substantial difference in steam pressure exists varying with the rate of flow of steam between said points in said system, fluid conducting means connected to said system at said points whereby steam tends to flow therethrough substantially in proportion to the rate of flow of steam between said points in said system, a lay-pass in said fluid conducting means arranged in parallel with a portion thereof and conducting fluid between spaced points in said fluid conducting means, means for controlling the flow through said fluid conducting means and said by-pass, and means in the said bypassed portion of said fluid conducting means responsive to the pressure differential across said by-passed portion and exerting measurable forces substantially proportionate to the rate of flow of steam in said system.

9. The combination of claim 8 in which said by-passed portion includes a depending loop in which condensate tends to stand while steam flows through said by-pass.

10. The combination of claim 8 in a boiler feed water system including a feed water Valve, with means connecting the said means in the said bypassed portion of said fluid conducting means and said valve to transmit forces therebetween to influence said valve with respect to the rate of flow of steam.

HENRY J. MASTENBROOK. 

